Preheating arrangement for internal combustion engines with fuel injection



K. WOLF 3,379,184 PREHEATING ARRANGEMENT FOR INTERNAL COMBUSTION Filed Aug. 1l, 1966 United States Patent PREHEATING ARRANGEMENT FOR INTERNAL COMBUSHUN ENGINES WITH FUEL INJECTIN Karl Wolf, Stuttgart-Sonnenberg, Germany, assignor to Robert Bosch, G.m.b.H., Stuttgart, Germany Filed Aug. 11, 1966, Ser. No. 571,900 Claims priority, application Germany, Aug. 17, 1965, B 83,284 Claims. (Cl. 123-179) The present invention relates to internal combustion engines in general, and more particularly to improvements in engines whose cylinders receive sprays of fuel from an injection pump. Still more particularly, the invention relates to improvements in arrangements which can be utilized to preheat the combustion chambers of such engines prior to admission of fuel sprays. The invention also relates to a novel valve lassembly which can be utilized in such preheating arrangements.

It is an important object of the present invention to provide a preheating arrangement which can invariably heat the combustion chambers of an internal combustion engine with fuel injection prior to actual admission of fuel by the injection pump.

Another object of the invention is to provide a preheating arrangement which becomes effective as soon as the fuel pump which is provided to deliver fuel to the injection pump is started.

A further object of the invention is to provide a novel and improved connection between the pressure outlet of a fuel pump and the electrically heated preheating device of the above outlined arrangement.

An additinal object of the invention is to provide an electrically controlled valve assembly which can be utilized with advantage in the connection between the fuel pump and the preheating device.

A concomitant object of the invention is to provide the valve assembly with a pressure-responsive valve which can effectively control the pressure of fuel admitted to the preheating device.

Briey stated, one feature of the present invention resides in the provision of a preheating `arrangement for internal combustion engines of the type having at least one `combustion chamber communicating with an intake manifold and wherein such chamber receives fuel from an injection pump which is supplied with fuel by piping connected to the pressure outlet of a fuel pump. The preheating arrangement comprises a preheating device eX- tending into the intake manifold, conduit means connecting the pressure outlet of the fuel pump with the preheating device, a valve assembly including a body installed in the conduit means, a valve member provided in the body for normally sealing the same to thus prevent the flow of fuel to the preheating device, an overflow line connected to the body, yand a irst pressure-responsive valve for regulating the ow of fuel from the conduit means into the overflow line, electric means for moving the valve member to open position and for simultaneously heating the preheating device so that such device ignites fuel delivered by the conduit means in response to starting of the fuel pump whereby the resulting llame preheats the combustion chamber of the engine, and preferably a second pressure-responsive valve provided in the piping between the fuel pump and the injection pump for delaying the admission of fuel to the injection pump so that the preheating device invariably receives fuel ahead of the injection pump.

The electrical means may comprise a control switch which can complete the circuit of the preheating device even before the valve member in the body of the aforementioned valve assembly is moved to open position and prior to starting a motor which operates the fuel pump. This contributes to satisfactory heating of the preheating device prior to admission of fuel thereto. The preheating arrangement of my invention has been found to be capable of delivering fuel to the preheating device in response to the every rst Working stroke of the fuel pump.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved preheating arrangement itself, however, both as to its constnuction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of a specific embodiment with reference to the accompanying drawings, in which:

FIG. 1 is an axial sectional view of a novel valve assembly which forms part of the preheating arrangement; and

FIG. 2 is a diagrammatic view of the preheating arrangement which embodies the valve assembly of FIG. 1, this valve assembly and certain other parts of the preheating arrangement being shown in section.

Referring first to FIG. 1, there is shown a valve assembly 1 including a valve body 12 which is a light metal casting and denes a space 2. When the preheating arrangement which embodies the valve assembly 1 of FIG. 1 is idle, the fuel admitting inlet 12a of the body 12 is sealed from the space 2 by a valve member 16 biased by a valve spring 16 and bearing against an annular seat 12b. A threaded nip-ple 13 meshing with the body 12 and extending into the inlet 12a is connected with a feed conduit 4a (see FlG. 2) which can deliver fuel in the direction indicated by an arrow a. The `outlet 12C of the body 12 accommodates a portion of a threaded nipple 3 connected to the inlet end of a supply `conduit 4 which can deliver fuel in the direction indicated by an arrow b and on to an electrically heated preheating device 5 (FIG. 2), such as a torch glow plug.

A channel 6 in the body 12 connects the outlet 12e with a second outlet 12d which receives the threaded end of a hollow valve housing 7a forming part of an adjustable pressure-responsive valve 7. The passage in the valve housing '7a is normally sealed by a disk-shaped valve element 9a which is biased by a valve spring 9 and bears against an annular seat 7b surrounding a portion of the passage in the housing 7a. The adjusting means for regulating the bias of the valve spring 9 comprises a hollow externally threaded plug 10 which meshes with the housing 7a and can be lixed in selected position by a lock nut 11". The plug 10 is further connected with an overflow line 8 which can convey surplus fuel in the direction indicated by an arrow c when the valve element 9a is caused to move away from the seat 7b.

The valve spring 9 may be adjusted in such a way that the pressure-responsive valve 7 will open to admit fuel from the space 2 into the overflow line S in response to a fuel pressure of between 0.3 and 0.6 atmosphere pressure. The overflow line 3 discharges into a fuel tank 29 shown in FIG. 2.

The body 12 of the valve assembly 1 further carries a solenoid 15 which serves as a part of electric means for moving the valve member 16 to open position, ie., away from the seat 12b. The housing of the solenoid 15 is attached to the body 12 and a silicone rubber gasket 14 insures that no fuel can leak from the upper end of the space 2. The solenoid 1S comprises a diamagnetic pusher 16 which can displace the valve member 16', a core 1'7 of soft iron which is connected to one end of the pusher 16 and is received in a brass sleeve 18, and a coil 19 which surrounds the sleeve 18 adjacent to the gasket 14. The ends of the coil 19 are connected with two terminals 19a,

19h which are respectively connectable to the positive and negative poles of a source of electrical energy. When the circuit of the coil 19 is completed, the latter attracts the core 17 so that the pusher 16 moves downwardly and shifts the valve member 16 away from the seat 12b. This enables fuel to fiow from the feed cond-uit 4a into the supply conduit 4 and thence to the preheating device 5. The valve 7 insures that the pressure of fuel which flows in the direction of the arrow b and into the device 5 cannot exceed a preselected pressure of not less than 0.3 and preferably not exceeding 0.6 atmosphere pressure.

The channel 6 in the body 12 forms part of a bore whose outer portion 6 is sealed by a brass screw 2t). This screw insures that, with the exception of the outlet 12C which is connected with the preheating device 5, all openings leading to or from the space 2 in the body 12 are Sealed from the atmosphere when the engine is idle. Since the outlet 12e is not sealed, the preheating device 5 will receive fuel without delay as soon as the coil 19 is energized and as soon as a fuel pump 28 (see FIG. 2) begins to supply fuel through the feed conduit 4a. Such non-delayed admission of fuel to the preheating device S will take place regardless of the length of intervals during which the engine is at a standstill.

The manner in which the valve assembly 1 of FIG. l is installed in the improved preheating arrangement is illustrated in FIG. 2. The aforementioned fuel pump 28 has its intake connected to the fuel tank 29 by means of a suction pipe 28a and its pressure outlet connected directiy to the feed conduit 4a. The pressure outlet of the fuel pump 28 is further connected with a pipe 21 serving to convey fuel to a filter 24 which is connected with a fuel injection pump 23 by a further pipe 22. The lter 24 has an overliow line 24a which is connected with the overflow line S. lf the valve 7 is adjusted to open, for example, in response to a fuel pressure of about 6.4 atmosphere pressure, some fuel admitted by the feed conduit 4a might escape through the overflow line 8 to return into the tank 29 as indicated by the arrow c.

The preheating arrangement shown in FIG. 2 is believed to be the first of its kind to operate effectively without necessitating the provision of a separate fuel tank or the provision of a separate fuel pump for the preheating device 5. This preheating device extends into an intake manifold 26 which communicates with the combustion chambers of the internal combustion engine. As explained above, the valve assembly 1 prevents leakage of fuel and its pressure-responsive valve 7 insures that the preheating device 5 receives fuel at a requisite optimum pressure. The preheating arrangement of FIG. 2 can operate properly with the parts which were described hereinbefore and insures that the combustion chambers are heated prior to admission of fuel sprays by the pipes e, f, g and h of the injection pump 23.

In order to further insure admission of fuel to the preheating device 5 without any undesirable delay, the pipe 21 preferably accommodates a second pressure-responsive valve 25 which can be adjusted by means of a threaded plug 25a and is located upstream of the filter 24 and preferably immediately adjacent to the pressure outlet to the fuel pump 28. The valve 25 is arranged to open in response to a fuel pressure of at least 0.2 atmosphere pressure. The provision of this pressure-responsive valve 25 in the pipe 21 which supplies fuel to the filter 24 and injection pump 23 insures that the latter receives fuel later than the preheating device 5. The preheating device 5 is electrically heated when the movable contact 27a of a control switch 27 connected into the circuit of the device 5 and solenoid 7 is shifted to a position 2 in which it engages a first fixed contact 27b. This also completes the circuit of the coil 19 so that the pusher 16 moves the valve member to open position and allows for unobstructed fiow of fuel from the pressure outlet of the fuel pump 28 into the preheating device. lt was found that the device 5 will receive fuel in response to the very first working stroke of the fuel pump 28 whereas the pipe 21 remains sealed by the valve 2S until the pump 2S builds up a pressure of at least 0.2 atmosphere pressure. Consequently, the preheating device 5 will receive fuel without delay, as soon as the pump 28 is started regardless of whether the pipes 21, 22, filter 24 and the injection pump 23 are partially empty or are filled with fuel. Since the preheating device 5 is heated even before the pump 28 begins to deliver fuel, there is no danger that the space in the intake manifold 26 would be enriched with uncombusted fuel.

Another advantageous feature of the preheating arrangement shown in FIG. 2 resides in the provision of a substantially cylindrical bellows 4t) which is installed in the supply conduit d and preferably resembles a short cylinder having a centrally located external annular groove 46a and consisting of silicone rubber or analogous elastomeric material which is an electrical insulator. This bellows 4f) defines an expansion chamber which stores some fuel during each working stroke of the fuel pump 28 and automatically delivers such fuel to the preheating device during the intervals between such working strokes. The provision of the bellows 40 is of particular importance when the fuel pump 28 is started and the intervals between, successive working strokes are relatively long. During each long intervals, the billows 40 prevents sudden and surge-like formation of flames because it keeps back some fuel during a working stroke and continues to deliver fuel to the preheating device 5 subsequent to the completed working stroke. As stated before, the material of the bellows 40 is an electrical insulator which isolates the preheating device 5 from the solenoid 15.

Surplus fuel which is free to escape yfrom the body 12 in response to opening of the valve 7 will fiow through the overflow line 8 and will returninto the tank 29, together with surplus fuel fiowing through the `overflow line 24a. A monitor 30 is connected in circuit with the preheating device 5 and indicates the condition of the preheating device 5 when the movable contacts 27a of the control switch 27 is held in the position 1, i.e., when the engine is at a standstill. This monitor 30 remains lighted when the engine is running. The arrow d indicates in FIG. 2 a conductor which is connected with a second fixed contact 27C. When the contact 27a is moved into engagement with the fixed contact 27e` (position 3), the starter motor of the engine begins to turn to operate the engine and the fuel pump 28 which then supplies fuel to the preheating device 5 at the time the latters temperature is high enough to ignite the fuel which is supplied through the conduit 4.

In the illustrated embodiment, the internal combustion engine is assumed to comprise four cylinders; therefore, the injection pump 23 has four separate pipes, e, f, g and h.

An important advantage of the-novel valve assembly 1 wherein the valve member 16 can be moved to open position by the solenoid 15 is that this assembly can insure timely admission of fuel to the preheating device 5 regardless of the temperature of the internal combustion engine. In many presently known preheating arrangements, the flow of fuel to the preheating device is controlled by thermally controlled valves whose operation is not independent of the temperature of the engine. Furthermore, the valve assembly 1 is particularly useful in such types of preheating arrangements wherein that portion of the intake manifold 26 which receives the device 5 is located at a level above the fueltank 29. Conventional preheating arrangements of such design invariably require a separate fuel tank which cannot be left empty when the engine is idle because, otherwise, too much elect trical energy and time would be consumed before the preheating device would be again in a condition to ignite the fuel. Therefore, such special fuel tanks for conventional preheating devices must be provided with valves which can seal them from the preheating device as well as from the conduit which delivers fuel thereto.

As stated before, the valve assembly' 1 of my invention automatically seals all inlets and outlets of the body 12 when the engine is idle, with the sole exception of the outlet 12e which is connected with the preheating device S. Therefore, the delivery of fuel to the device 5 begins in immediate response to starting of the fuel pump 28 and independently of the momentary temperature of the internal combustion engine. The fuel pump 28 immediately builds up such pressure which is necessary to supply fuel into the preheating device, regardless of the length of intervals between sucessive working strokes of this pump. Such intervals can be quite long when the pump 23 is Set in motion. Also, the valve 7 insures that the pressure of fuel in the conduit 4 cannot rise beyond a preselected maximum value, regardless of the speed of the internal combustion engine.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specic aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be Letters Patent is:

1. A valve assembly for use in preheating arrangements of internal combustion engines, particularly for controlling the flow of fuel to the electrically heated preheating device in the intake manifold of an internal combustion engine with fuel injection, comprising a body defining a space, a fuel-admitting inlet communicating with said space, and an outlet for discharging fuel from said space; a solenoid-operated valve member for controlling the admission of fuel via said inlet; an overflow line connected with said body and communicating with said space; and a pressure-responsive valve for regulating the admission of fuel from said space into said overflow line.

2. A valve assembly as set forth in claim 1, further comprising a supply conduit connecting said outlet with the preheating device.

3. A valve assembly as set forth in claim 1, wherein said body is provided with a channel connecting Said outlet with said overiow line.

4. A valve assembly as set forth in claim l, wherein said pressure-responsive valve is arranged to open in response to a fuel pressure of between @.3 and 0.6 atmosphere pressure.

5. A valve assembly as set forth in claim 4, further comprising adjusting means for selecting the exact fuel pressure which opens said pressure-responsive valve.

6. A valve assembly as set forth in claim 5', wherein said pressure-responsive valve comprises a housing connected with said body and with said overilow line and defining a passage for fuel and a seat surrounding a portion of said. passage, a valve element received in said housing, and a valve spring for biasing said valve element against said seat, said adjusting means comprising a threaded member meshing with and rotatable with reference to said housing to thereby change the bias of said Valve spring.

7. A valve assembly as set forth in claim 6, wherein said threaded member is hollow and is connected with the intake end of said -overiiow line.

8. A preheating arrangement for internal combustion engines of the type having at least one combustion charnber communicating with an intake manifold and wherein such chamber receives fuel from an injection pump which protected by is supplied with fuel by piping connected to the pressure outlet of a fuel pump, said preheating arrangement comprising a preheating device extending into the intake manifold; conduit means connecting the pressure outlet of the fuel pump with said preheating device; a valve assembly including a body installed in said conduit means, a Valve member provided in said body for normally sealing the same to prevent the tiow of fuel to said preheating device, an overflow line connected to said body, and a first pressure-responsive valve for regulating the flow of fuel from said conduit means into said overiow line; electric means for moving said valve member to open position and for simultaneously heating said preheatirtg device so that said device ignites the fuel delivered by said conduit means in response to starting of the fuel pump whereby the resulting flame preheats the combustion chamber of the engine; and a second pressure-responsive valve provided in the piping between the fuel pump and the injection pump for delaying the admission of fuel to the injection pump so that the preheating device invarialbly receives fuel ahead of the injection pump.

9. A preheating arrangement as set forth in claim S, wherein said electric means includes a solenoid having a coil energizable to move said valve member to open position and wherein said second pressure-responsive valve is arranged to open and to admit fuel to the injection pump in response to a fuel pressure of at least 0.2 atmospheres pressure.

1d. A preheating arrangement as set forth in claim 8, wherein said first pressure responsive valve is arranged to open in response to a fuel pressure which exceeds the pressure necessary to open said second pressure-responsive valve.

1l. A preheating arrangement as set forth in claim 8, yfurther comprising an expansion chamber provided in said conduit means downstream of said .body and arranged to :store some of the fuel delivered by said conduit means during successive working strokes of the fuel pump and to automatically admit the thus stored fuel to said preheating device durinfy the intervals between such strokes.

l2. A preheating arrangement as set forth in claim 11, wherein Said expansion chamber is defined by a substantially cylindrical bellows consisting of silicone rubber.

13. A preheating arrangement as set forth in claim il, wherein said expansion chamber is defined by an elastic bellows constituting an electric insulator between said body and said preheating device.

14S. A preheating arrangement as set forth in claim 8, wherein said overflow line discharges into the fuel tank for the internal combustion engine and wherein the piping between the fuel pump and the injection pump accommodates a fuel filter located downstream of said second pressure-responsive valve and having an overflow line connected with said first mentioned overflow line.

15. A preheating arrangement as set forth in claim wherein said electric means comprises a control switch which is arranged to complete the circuit of said preheating device and to effect movement of said valve member to open position prior to starting of the motor which operates the fuel pump and turns the engine during starting.

References Cited UNlTED STATES PATENTS 2,229,714 1/1941 Wirrer 123-27 2,398,094 4/1946 Heymann l23-l22 2,993,487 7/1961 Konrad et ai. 123-179 X 3,338,226 8/1967 Claris 123-122 X 3,353,520 11/1967 Haag 12S-122 X AL LAWRENCE SMITH, Primary Examiner. 

1. A VALVE ASSEMBLY FOR USE IN PREHEATING ARRANGEMENTS OF INTERNAL COMBUSTION ENGINES, PARTICULARLY FOR CONTROLLING THE FLOW OF FUEL TO THE ELECTRICALLY HEATED PREHEATING DEVICE IN THE INTAKE MANIFOLD OF AN INTERNAL COMBUSTION ENGINE WITH FUEL INJECTION, COMPRISING A BODY DEFINING A SPACE, A FUEL-ADMITTING INLET COMMUNICATING WITH SAID SPACE, AND AN OUTLET FOR DISCHARGING FUEL FROM SAID SPACE; A SOLENOID-OPERATED VALVE MEMBER FOR CONTROLLING THE ADMISSION OF FUEL VIA SAID INLET; AN OVERFLOW LINE CONNECTED WITH SAID BODY AND COMMUNICATING WITH SAID SPACE; AND A PRESSURE-RESPONSIVE VALVE FOR REGULATING THE ADMISSION OF FUEL FROM SAID SPACE INTO SAID OVERFLOW LINE.
 8. A PREHEATING ARRANGEMENT FOR INTERNAL COMBUSTION ENGINES OF THE TYPE HAVING AT LEAST ONE COMBUSTION CHAMBER COMMUNICATING WITH AN INTAKE MANIFOLD AND WHEREIN SUCH CHAMBER RECEIVES FUEL FROM AN INJECTION PUMP WHICH IS SUPPLIED WITH FUEL BY PIPING CONNECTED TO THE PRESSURE OUTLET OF A FUEL PUMP, SAID PREHEATING ARRANGEMENT COMPRISING A PREHEATING DEVICE EXTENDING INTO THE INTAKE MANIFOLD; CONDUIT MEANS CONNECTING THE PRESSURE OUTLET OF THE FUEL PUMP WITH SAID PREHEATING DEVICE; A VALVE ASSEMBLY INCLUDING A BODY INSTALLED IN SAID CONDUIT MEANS, A VALVE MEMBER PROVIDED IN SAID BODY FOR NORMALLY SEALING THE SAME TO PREVENT THE FLOW OF FUEL TO SAID PREHEATING 